Flexible substrate, manufacturing method for flexible substrate and display device

ABSTRACT

The present disclosure provides a flexible substrate, the flexible substrate is divided into a display region, a binding region on a side of the display region, a to-be-bent region between the display region and the binding region, two transition regions between the to-be-bent region and the display region and between the to-be-bent region and the binding region respectively; the transition regions comprise a plurality of transition sub-regions arranged in a first direction, the first direction is a direction from the display region to the binding region; the flexible substrate comprises a flexible base and a back film disposed on the flexible base, a portion of the back film is located in the transition regions; in any one of the transition regions, the amount of distribution per unit area of the back film in each of the transition sub-regions gradually decreases in a direction gradually approaching the to-be-bent region.

CROSS-REFERENCE TO RELATED APPLICATION

This is a National Phase Application filed under 35 U.S.C. 371 as anational stage of PCT/CN2018/112388, filed on Oct. 29, 2018, anapplication claiming the priority of China Application No.201810162327.7, filed on Feb. 27, 2018 to China National IntellectualProperty Administration (CNIPA), entitled “FLEXIBLE SUBSTRATE,MANUFACTURING METHOD FOR FLEXIBLE SUBSTRATE AND DISPLAY DEVICE”, theentire contents of each of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to the field of display technologies, andin particular to a flexible substrate, a manufacturing method thereofand a display device.

BACKGROUND

In the display device, one side of a display area of a display substrateis provided with a binding electrode for transmitting an electricalsignal of a driving circuit to the display area. In the conventionaltechnology, after the flexible circuit board is electrically connectedto the binding electrode, the flexible circuit board is bent to the sideof the display substrate facing away from the display. In order toreduce the width of the border of the display device, the manufacturerbegan to gradually adopt a flexible display panel, and directly bend theflexible substrate therein to bend the binding region to the back of theflexible substrate, so as to reduce the bending radius. However, atpresent, after the flexible substrate is bent, the initial position ofthe bending region is prone to breakage of the signal line.

SUMMARY

The present disclosure provides a flexible substrate, wherein theflexible substrate is divided into a display region, a binding region ona side of the display region, a to-be-bent region between the displayregion and the binding region, two transition regions between theto-be-bent region and the display region and between the to-be-bentregion and the binding region respectively; the transition regionscomprise a plurality of transition sub-regions arranged in a firstdirection, the first direction is a direction from the display region tothe binding region; the flexible substrate comprises a flexible base anda back film disposed on the flexible base, a portion of the back film islocated in the transition regions; in any one of the transition regions,the amount of distribution per unit area of the back film in each of thetransition sub-regions gradually decreases in a direction graduallyapproaching the to-be-bent region.

Alternatively, a thickness of the back film in any one of the transitionregions gradually decreases in the direction gradually approaching theto-be-bent region.

Alternatively, a thickness of the back film in any one of the transitionsub-regions remains constant or gradually decreases in the directiongradually approaching the to-be-bent region.

Alternatively, in any one of the transition regions, a coverage rate ofthe back film in each of the transition sub-regions gradually decreasesin the direction gradually approaching the to-be-bent region.

Alternatively, the portion of the back film located in the transitionregions comprises a plurality of transition pattern portions, theplurality of transition pattern portions are arranged in a seconddirection perpendicular to the first direction; a size of the transitionpattern portions in the second direction gradually decreases from a sideof the transition pattern portions away from the to-be-bent region to aside of the transition pattern portions close to the to-be-bent region.

Alternatively, a portion of the back film located outside the transitionregions is disposed in the display region and the binding region, athickness of the back film in both the display region and the bindingregion is greater than or equal to the thickness of the back film in thetransition regions.

Alternatively, an adhesive layer is further disposed between the backfilm and the flexible base, the adhesive layer covers the entireflexible base.

Correspondingly, the present disclosure further provides a manufacturingmethod for flexible substrate, the flexible substrate being divided intoa display region, a binding region on a side of the display region, ato-be-bent region between the display region and the binding region, twotransition regions between the to-be-bent region and the display regionand between the to-be-bent region and the binding region respectively;the transition regions comprising a plurality of transition sub-regionsarranged in a first direction, the first direction being a directionfrom the display region to the binding region; the manufacturing methodcomprising: providing a flexible base; forming a back film on theflexible base; wherein a portion of the back film is located in thetransition regions; in any one of the transition regions, the amount ofdistribution per unit area of the back film in each of the transitionsub-regions gradually decreases in a direction gradually approaching theto-be-bent region.

Alternatively, the step of forming a back film on the flexible basecomprises: forming an initial back film; performing laser etching on theinitial back film to form the back film.

Alternatively, the step of performing laser etching on the initial backfilm comprises: performing a first etching process on a portion of theinitial back film located in the transition regions such that athickness of the back film in any one of the transition regionsgradually decreases in the direction gradually approaching theto-be-bent region.

Alternatively, the thickness of the back film in any one of thetransition sub-regions remains constant or gradually decreases in thedirection gradually approaching the to-be-bent region.

Alternatively, the first etching process comprises etching the initialback film at least once in each of the transition sub-regions, and thenumber of etchings performed in each of the transition sub-regionsgradually increases in the direction gradually approaching theto-be-bent region.

Alternatively, the step of performing laser etching on the initial backfilm comprises: performing a second etching process on a portion of theinitial back film located in the transition regions, such that in anyone of the transition regions, a coverage rate of the back film in eachof the transition sub-regions gradually decreases in the directiongradually approaching the to-be-bent region.

Alternatively, the portion of the back film located in the transitionregions comprises a plurality of transition pattern portions, theplurality of transition pattern portions are arranged in a seconddirection perpendicular to the first direction; and a size of thetransition pattern portions in the second direction gradually decreasesfrom a side of the transition pattern portions away from the to-be-bentregion to a side of the transition pattern portions close to theto-be-bent region.

Alternatively, a portion of the back film located outside the transitionregions is disposed in the display region and the binding region, athickness of the back film in both the display region and the bindingregion is greater than or equal to the thickness of the back film in thetransition regions.

Alternatively, the step of forming the back film on the flexible basefurther comprises: forming an adhesive layer on the flexible base, theback film is located on a side of the adhesive layer away from theflexible base.

Correspondingly, the present disclosure further provides a displaydevice comprising a display substrate obtained by bending a flexiblesubstrate described above along a to-be-bent region of the flexiblesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are intended to provide a furtherunderstanding to disclosure and form part of the specification forexplaining the disclosure in conjunction with the following specificembodiments, but are not intended to limit to the disclosure. In thedrawings:

FIG. 1 is a schematic view of a flexible substrate in the related art;

FIG. 2 is a schematic view of the flexible substrate of FIG. 1 afterbeing bent;

FIG. 3 is a plan view of a flexible substrate in an embodiment of thepresent disclosure;

FIG. 4 is a first cross-sectional view taken along line BB of FIG. 3;

FIG. 5 is a second cross-sectional view taken along line BB of FIG. 3;

FIG. 6 is a third cross-sectional view taken along line BB of FIG. 3;

FIG. 7 is a schematic view showing a state of a flexible substrate afterbeing bent in the present disclosure;

FIG. 8 is a plan view of a flexible substrate in an embodiment of thepresent disclosure;

FIG. 9 is a first cross-sectional view taken along line CC of FIG. 8;

FIG. 10 is a second cross-sectional view taken along line CC of FIG. 8;

FIG. 11 is a plan view of a flexible substrate in an embodiment of thepresent disclosure;

FIG. 12 is a flow chart of a manufacturing method for a flexiblesubstrate provided by the present disclosure; and

FIGS. 13a to 13d are flow charts of a first etching process in amanufacturing method for a flexible substrate.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The specific embodiments of the present disclosure will be described indetail below with reference to the accompanying drawings. It is to beunderstood that the specific embodiments described herein are forillustrative purposes only and are not intended to limit the disclosure.

FIG. 1 is a schematic view of a flexible substrate in the related art.The flexible substrate includes a flexible base 11 having opposing firstand second surfaces. The first surface of the flexible base 11 isprovided with a display device (not shown), and the second surface ofthe flexible base 11 is provided with a back film 12. The flexiblesubstrate is divided into a display region AA, a binding region BO, anda space region M between the display region AA and the binding regionBO. The display region AA is provided with a signal end, the bindingregion BO is provided with a binding electrode, and the signal end andthe binding electrode are connected by a signal line. In order to reducethe border of the display product, the binding region BO needs to bebent to the back of the display region AA. Since the hardness of theback film 12 is relatively large, in order to achieve the desiredbending radius, the back film in the space region M needs to be removed,and then the space region is bent, thereby obtaining the structure inFIG. 2. In FIG. 2, at the starting positions of the bending (Position aand Position b), the flexible base 11 is abruptly changed from a flatstate to a curved state, and a thickness of the back film 12 is alsoabruptly changed. Therefore, stress concentration would be occurred atthe starting positions of the bending. The thickness of the flexiblebase 11 is usually very thin, which tends to cause breakage of thesignal line on the flexible base 11. In particular, when the bendingshape is adjusted, the display region AA and the binding region BO arerelatively moved in a left-right direction of FIG. 2. This makes iteasier to cause the flexible base 11 to be subjected to a large force atthe Position a and the Position b, resulting in breakage of the signalline.

In order to reduce breakage of the signal line when the flexiblesubstrate is bent, an embodiment of the present disclosure provides aflexible substrate. Referring to FIGS. 3 to 6, the flexible substrateincludes a flexible base 11 and a back film 12 disposed on the flexiblebase 11. The flexible substrate is divided into a display region AA, abinding region BO on a side of the display region AA, a to-be-bentregion BE between the display region AA and the binding region BO, twotransition regions TA between the to-be-bent region BE and the displayregion AA and between the to-be-bent region BE and the binding region BOrespectively. The transition regions TA include a plurality oftransition sub-regions TA′ arranged in a first direction, the firstdirection is a direction from the display region AA to the bindingregion BO (i.e., the direction from left to right in FIG. 3). A portionof a back film 12 is located in the transition regions TA. In any one ofthe transition regions TA, the amount of distribution per unit area ofthe back film 12 in each of the transition sub-regions TA′ graduallydecreases in a direction gradually approaching the to-be-bent region BE.

It should be noted that the amount of distribution per unit area refersto the volume per unit area. The amount of distribution per unit area ofthe back film 12 in each of the transition sub-regions TA′ means theratio of the volume of the back film 12 in the transition sub-region TA′to the area of the transition sub-region TA′. Therefore, “the amount ofdistribution per unit area of the back film 12 in each of the transitionsub-regions TA′ gradually decreases in a direction gradually approachingthe to-be-bent region BE” means that the closer a transition sub-regionTA′ is to the to-be-bent region BE, the smaller the amount ofdistribution per unit area of the back film 12 in the transitionsub-region (the smaller the average volume per unit area) compared toother transition sub-regions farther away from the to-be-bent region BE.

Compared with the related art, in the flexible substrate in the presentdisclosure, since the amount of the back film 12 in the transitionregions TA is not directly changed from a large amount to zero, but hasa gradually decreasing transition process. When the to-be-bent region BEis bent, the problem of stress concentration does not occur, and thephenomenon that breakage of the signal line on the flexible base 11 dueto a large stress is decreased. For example, as shown in FIG. 7, theportion of the flexible base 11 located in the transition regions TAsmoothly transits into an arc shape, so that the back film 12 is nolonger changed significantly at the starting position of the bending.Therefore, the problem of stress concentration does not occur.Similarly, as shown in FIG. 8, for example, the back film 12 is formedinto a specific pattern in the transition regions TA, such that theamount of distribution per unit area of the back film in the transitionsub-region TA′ near the to-be-bent region BE decreases, compared withthe amount of distribution per unit area of the back film in the othertransition sub-regions TA′ away from the to-be-bent region BE.Therefore, the stress of the back film 12 at the starting position ofthe bending does not change significantly, and the problem of stressconcentration does not occur.

The area of the transition regions TA may be 0.5 to 2 times the area ofthe to-be-bent region BE.

In a specific embodiment of the present disclosure, the change in theamount of distribution per unit area of the back film in each transitionsub-region TA′ can be achieved by the change in the thickness of theback film 12. Specifically, the thickness of the back film 12 in any oneof the transition regions TA gradually decreases in a directiongradually approaching the to-be-bent region BE. Herein, “graduallydecrease” can be continuously decrease or intermittently decrease. Forexample, the thickness of the back film 12 may remain constant in aportion of the transition regions TA.

Further, in the same transition sub-region TA′ of one transition regionTA, the thickness of the back film 12 may be uniformly distributed ormay be gradually changed. Specifically, as shown in FIG. 4, thethickness of the back film 12 in any one of the transition sub-regionsTA′ remains constant in the direction gradually approaching theto-be-bent region BE, so that the thickness of the back film 12 variesstepwise throughout the transition regions TA. Alternatively, as shownin FIGS. 5 and 6, the thickness of the back film 12 in any one of thetransition sub-regions TA′ gradually decreases in the directiongradually approaching the to-be-bent region BE, so that the back film 12has an inclined plane (as shown in FIG. 6), a convex curved surface or aconcave curved surface (as shown in FIG. 5) throughout the transitionregions TA.

As shown in FIG. 3, in one embodiment, the back film 12 can completelycover the transition regions TA.

In a specific embodiment of the present disclosure, the change in theamount of distribution per unit area of the back film 12 in eachtransition sub-region TA′ can be achieved by the change in the coveragerate of the back film 12 in each transition sub-region TA′.Specifically, in any one of the transition regions TA, the coverage rateof the back film 12 in each of the transition sub-regions TA′ graduallydecreases in the direction gradually approaching the to-be-bent regionBE. It should be noted that the coverage rate of the back film 12 in anyone of the transition sub-regions TA′ is the ratio of the coverage areaof the back film 12 in a transition sub-region TA′ to the area of thetransition sub-region TA′.

In order to make the force distribution at each position in the sametransition sub-region TA′ uniform when the flexible base 11 bends, andmore specifically, as shown in FIGS. 8 and 11, the portion of the backfilm 12 located in the transition regions TA includes a plurality oftransition pattern portions 12 a, the plurality of transition patternportions 12 a are arranged in a second direction perpendicular to thefirst direction. In FIGS. 8 and 11, the first direction is the left andright direction, and the second direction is the up and down direction.A size of the transition pattern portions 12 a in the second directiongradually decreases from a side of the transition pattern portions 12 aaway from the to-be-bent region BE (left side in the figure) to a sideof the transition pattern portions 12 a close to the to-be-bent regionBE (right side in the figure). The orthographic shape of each transitionpattern portion 12 a on the flexible base 11 may be a triangle (as shownin FIG. 8), or a part of an ellipse (as shown in FIG. 11), or may beother shape.

In a specific embodiment, the thickness of each position in the same onetransition pattern portion 12 a may be the same. In order to realize anarrow border, various embodiments may be combined such that when theflexible base 11 is bent, the closer a position of the flexible base 11is to the to-be-bent region BE, the smaller the force is applied,thereby it is advantageous to reduce the bending radius. Specifically,as shown in FIGS. 8 and 9, with respect to any one of the transitionpattern portions 12 a, the thickness of the transition pattern portion12 a in the transition regions TA gradually decreases in the directiongradually approaching the to-be-bent region BE, and the transitionpattern portion 12 a has the same thickness in the same one transitionsub-region TA′. Alternatively, as shown in FIGS. 8 and 10, with respectto any one of the transition pattern portions 12 a, the thickness of thetransition pattern portion 12 a gradually decreases in the directiongradually approaching the to-be-bent region BE.

Considering that if the back film 12 also has a certain thickness in theto-be-bent region BE, the back film 12 of the to-be-bent region BE issqueezed to form a bulge when bent, so that a part of the signal linelocated at the to-be-bent region BE is broken or of other defects. Tothis end, in the present disclosure, the portion of the back film 12located outside the transition regions TA is disposed in the displayregion AA and the binding region BO, and the back film is not providedin the to-be-bent region BE. In addition, the thickness of the back film12 in the display region AA and the binding region BO is greater than orequal to the thickness of the back film 12 in the transition regions TA,respectively.

Further, an adhesive layer 13 is further disposed between the back film12 and the flexible base 11, and the adhesive layer 13 covers the entireflexible base 11. The adhesive layer 13 is used to bond the back film 12to the flexible base 11. In addition, the adhesive layer 13 can preventthe flexible base 11 from being damaged when the back film 12 in theto-be-bent region BE is removed.

Correspondingly, the present disclosure further provides a manufacturingmethod for flexible substrate. As shown in FIGS. 3 to 6, the flexiblesubstrate is divided into a display region AA, a binding region on aside of the display region AA, a to-be-bent region BE between thedisplay region AA and the binding region BO, and two transition regionsTA between the to-be-bent region BE and the display region AA andbetween the to-be-bent region BE and the binding region BO,respectively. The transition regions TA include a plurality oftransition sub-regions TA′ arranged in a first direction, the firstdirection is a direction from the display region AA to the bindingregion BO. The manufacturing method includes:

providing a flexible base;

forming a back film on the flexible base; wherein a portion of the backfilm is located in the transition regions; in any one of the transitionregions, the amount of distribution per unit area of the back film ineach of the transition sub-regions gradually decreases in a directiongradually approaching the to-be-bent region.

Since the amount of the back film in the transition regions is notdirectly changed from a large amount to zero, but has a graduallydecreasing transition process. Therefore, when the to-be-bent region isbent, the portion of the flexible base located in the transition regionssmoothly transits into an arc shape, so that the back film is no longerchanged significantly at the starting position of the bending.Therefore, the problem of stress concentration does not occur, and thephenomenon that breakage of the signal line at the starting position ofthe bending on the flexible base due to a large stress is decreased.

The manufacturing method for flexible substrate of the presentdisclosure will be described in detail below with reference to FIG. 12.The flexible substrate is divided into the above display region, bindingregion, to-be-bent region and transition region. The manufacturingmethod includes the following steps S10˜S30:

S10: providing a flexible base.

S20: forming an adhesive layer on the flexible base.

S30: forming a back film on the flexible base; wherein the back film ison a side of the adhesive layer away from the flexible base. A portionof the back film is located in the transition regions; another portionof the back film is located in the display region and binding region. Athickness of the back film in both the display region and the bindingregion is greater than or equal to the thickness of the back film in thetransition regions. In any one of the transition regions, the amount ofdistribution per unit area of the back film in each of the transitionsub-regions gradually decreases in a direction gradually approaching theto-be-bent region.

The step S30 specifically includes:

S31: forming an initial back film. The initial back film may cover theentire flexible base, and the material of the initial back film may bepolyethylene terephthalate (PET).

S32: performing laser etching on the initial back film to form the backfilm. Specifically, a portion of the initial back film located in theto-be-bent region and the transition region is laser etched to form theback film.

Wherein, the amount of distribution per unit area of the back film ineach transition sub-region can be gradually changed by controlling thethickness of the back film. At this time, the step S32 may specificallyinclude:

S32 a: performing a first etching process on a portion of the initialback film located in the to-be-bent region and transition regions suchthat a thickness of the back film in any one of the transition regionsgradually decreases in the direction gradually approaching theto-be-bent region. Alternatively, the thickness of the back film in anyone of the transition sub-regions remains constant or graduallydecreases in the direction gradually approaching the to-be-bent region.

Alternatively, the first etching process includes etching the initialback film at least once in each of the transition sub-regions, and thenumber of etchings performed in each of the transition sub-regionsgradually increases from a side of the transition regions away from theto-be-bent region BE to a side of the transition regions close to theto-be-bent region. Wherein, the etching depth of each etching may be thesame, so that the closer the transition sub-region to the to-be-bentregion is, the more the thickness of the initial back film is etchedaway. By adopting this multiple etching method, it can prevent largedepths of one-time etching and generating a large amount of heat.Therefore, the local heat of the initial back film is prevented frombeing too high; and in the back film formed by etching, the propertiesof the material at the respective positions are similar, which is morefavorable for bending.

In actual production, the first etching in all transition sub-regionsmay be the same laser etching process, and the second etching on aportion of the transition sub-regions is the same laser etching process.Taking two transition sub-regions on both sides of the to-be-bent regionas an example, FIGS. 13a to 13d are schematic flow diagrams of the firstetching process. After the adhesive layer 13 and the initial back film121 are formed on the flexible base 11 (as shown in FIG. 13a ), theinitial back film 121 of each transition sub-region TA′ and the initialback film 121 of the to-be-bent region BE are etched by a first laseretching process; and the etching result is as shown in FIG. 13b .Thereafter, the initial back film 121 of the to-be-bent region BE andits adjacent two transition sub-regions TA′ is etched by a second laseretching process, and the etching result is as shown in FIG. 13c .Finally, the initial back film 121 of the to-be-bent region BE is etchedby a third laser etching process, and the etching result is as shown inFIG. 13d . Similarly, when a number (for example, three) of thetransition sub-regions TA′ are respectively disposed on each side of theto-be-bent region, after subtracting one transition sub-region TA′ (fromeach side of the region toward the to-be-bent region BE) from the regionformed by the previous etching, the remaining region is where the nextetching is performed.

Definitely, the first etching process may also be such that the etchingdepth in each transition sub-region is gradually changed by controllingthe laser energy or by controlling the etching time. Alternatively, theinitial back film in the transition region (i.e., each transitionsub-region) is completely etched by the first etching process.

The above step S32 a is to gradually change the amount of distributionper unit area of the back film in each transition sub-region bycontrolling the thickness. In addition, it is also possible to graduallychange the amount of distribution per unit area of the back film in eachtransition sub-region by controlling the coverage rate. At this time,step S32 may include:

S32 b: performing a second etching process on a portion of the initialback film located in the transition regions, such that in any one of thetransition regions, a coverage rate of the back film in each of thetransition sub-regions gradually decreases in the direction graduallyapproaching the to-be-bent region. Specifically, the portion of the backfilm located in the transition regions includes a plurality oftransition pattern portions, the plurality of transition patternportions are arranged in a second direction perpendicular to the firstdirection. The size of the transition pattern portions in the seconddirection gradually decreases from a side of the transition patternportions away from the to-be-bent region to a side of the transitionpattern portions close to the to-be-bent region.

It should be noted that the foregoing step S32 may include only one ofthe steps S32 a and S32 b; or may include both. When the step S32includes the steps S32 a and S32 b, the order of the steps S32 a and S32b is not limited.

Correspondingly, the present disclosure further provides a displaydevice including a display substrate, wherein the display substrate isobtained by bending the flexible substrate along a to-be-bent region ofthe flexible substrate. After bending, the binding region is located onthe opposite side of the display region, and the to-be-bent region andat least a portion of each transition region together form a curvedstructure.

It is to be understood that the above embodiments are merely exemplaryembodiments employed to explain the principles of the presentdisclosure, but the present disclosure is not limited thereto. Variousmodifications and improvements can be made by those skilled in the artwithout departing from the spirit and scope of the disclosure, and suchmodifications and improvements are also considered to be within thescope of the disclosure.

What is claimed is:
 1. A flexible substrate, wherein the flexiblesubstrate is divided into a display region, a binding region on a sideof the display region, a to-be-bent region between the display regionand the binding region, two transition regions between the to-be-bentregion and the display region and between the to-be-bent region and thebinding region respectively; the transition regions comprise a pluralityof transition sub-regions arranged in a first direction, the firstdirection is a direction from the display region to the binding region;the flexible substrate comprises a flexible base and a back filmdisposed on the flexible base, a portion of the back film is located inthe transition regions; in any one of the transition regions, the amountof distribution per unit area of the back film in each of the transitionsub-regions gradually decreases in a direction gradually approaching theto-be-bent region; wherein in any one of the transition regions, acoverage rate of the back film in each of the transition sub-regionsgradually decreases in the direction gradually approaching theto-be-bent region, wherein the portion of the back film located in thetransition regions comprises a plurality of transition pattern portions,the plurality of transition pattern portions are arranged in a seconddirection perpendicular to the first direction; and a size of thetransition pattern portions in the second direction gradually decreasesfrom a side of the transition pattern portions away from the to-be-bentregion to a side of the transition pattern portions close to theto-be-bent region.
 2. The flexible substrate according to claim 1,wherein a thickness of the back film in any one of the transitionregions gradually decreases in the direction gradually approaching theto-be-bent region.
 3. The flexible substrate according to claim 2,wherein a thickness of the back film in any one of the transitionsub-regions remains constant or gradually decreases in the directiongradually approaching the to-be-bent region.
 4. The flexible substrateaccording to claim 1, wherein a portion of the back film located outsidethe transition regions is disposed in the display region and the bindingregion, a thickness of the back film in both the display region and thebinding region is greater than or equal to the thickness of the backfilm in the transition regions.
 5. The flexible substrate according toclaim 4, wherein an adhesive layer is further disposed between the backfilm and the flexible base, the adhesive layer covers the entireflexible base.
 6. A display device comprising a display substrateobtained by bending a flexible substrate according to claim 1 along ato-be-bent region of the flexible substrate.
 7. A manufacturing methodfor flexible substrate, the flexible substrate being divided into adisplay region, a binding region on a side of the display region, ato-be-bent region between the display region and the binding region, twotransition regions between the to-be-bent region and the display regionand between the to-be-bent region and the binding region respectively;the transition regions comprising a plurality of transition sub-regionsarranged in a first direction, the first direction being a directionfrom the display region to the binding region; the manufacturing methodcomprising: providing a flexible base; forming a back film on theflexible base; wherein a portion of the back film is located in thetransition regions; in any one of the transition regions, the amount ofdistribution per unit area of the back film in each of the transitionsub-regions gradually decreases in a direction gradually approaching theto-be-bent region, wherein the portion of the back film located in thetransition regions comprises a plurality of transition pattern portions,the plurality of transition pattern portions are arranged in a seconddirection perpendicular to the first direction; and a size of thetransition pattern portions in the second direction gradually decreasesfrom a side of the transition pattern portions away from the to-be-bentregion to a side of the transition pattern portions close to theto-be-bent region.
 8. The manufacturing method according to claim 7,wherein the step of forming a back film on the flexible base comprises:forming an initial back film; performing laser etching on the initialback film to form the back film.
 9. The manufacturing method accordingto claim 8, wherein the step of performing laser etching on the initialback film comprises: performing a first etching process on a portion ofthe initial back film located in the transition regions such that athickness of the back film in any one of the transition regionsgradually decreases in the direction gradually approaching theto-be-bent region.
 10. The manufacturing method according to claim 9,wherein the thickness of the back film in any one of the transitionsub-regions remains constant or gradually decreases in the directiongradually approaching the to-be-bent region.
 11. The manufacturingmethod according to claim 9, wherein the first etching process comprisesetching the initial back film at least once in each of the transitionsub-regions, and the number of etchings performed in each of thetransition sub-regions gradually increases in the direction graduallyapproaching the to-be-bent region.
 12. The manufacturing methodaccording to claim 11, wherein the step of performing laser etching onthe initial back film comprises: performing a second etching process ona portion of the initial back film located in the transition regions,such that in any one of the transition regions, a coverage rate of theback film in each of the transition sub-regions gradually decreases inthe direction gradually approaching the to-be-bent region.
 13. Themanufacturing method according to claim 11, wherein the step of formingthe back film on the flexible base further comprises: forming anadhesive layer on the flexible base, the back film is located on a sideof the adhesive layer away from the flexible base.
 14. The manufacturingmethod according to claim 7, wherein a portion of the back film locatedoutside the transition regions is disposed in the display region and thebinding region, a thickness of the back film in both the display regionand the binding region is greater than or equal to the thickness of theback film in the transition regions.